Hydrindole-indophenols and process of making the same



Patented st. 28, I 1930 uuirso STATES PATENTIOFFIQE;

FRITZ BALLA'UF, 0F .ELBERFELD, GERMANY,ASSIGNOR 'IO GENEBAL ANILINE WORKS,

me, or EW ORK, n. Y.,' A conronnrron or DELAWARE nvnnrnnonn-rnnornnnons Ann rzsocnss or MAKING THE SAME- No Drawing. Application filed October 25,1926, Serial No; 144,188, and in Germany November 2, 1925..

My invention pertains to processes of producing indophenol compounds containing. a dihydroindole' nucleus and to these novel indophenol compounds themselves;

Aromatic para-amino-hydroxy compounds are known to condensebyvarious reactions with aromatic amines to form indophenols or I the corresponding leucoindophenols.

,I have now :found that byireplacing the known aromatic amines in these reactions by certain dihydroin dolecompounds novel and very, valuable 'indophenolic bodies are obtained. This was, quite unexpected, asthe corresponding unhydrogenated: indole'sl do 5 not behave in the sameimanner and it has a not been possible yet to produce indophenolic bodies from such indoles.

The dihydroindoles which I found to readily react with aromatic para-amino-hydroxy 0 compounds to form lndophenohc bodies are of the general formula:

7 31 v on In this formulaflR stands for hydrogen, or

an aryl, alkyl or, an aralkyl, 'roup R stands for abenzene nucleus, which may be substituted e. g. by alkyl, aryl, aralliyl f halogen or other monovalent group.

primarily formed. They dissolve inaqueous alkalis with intense red to blue colors. 1 7

Reducing agents precipitate from the soluspondingdark tions of the indophenols the corresponding These novel leucoindo leuco compounds. phenols,- contalnlng the dihydrolndole nucleus are usually yellow colored crystalline substances, easily soluble in water, alcohol and sulfuric acid, but much less soluble inw salt solutions. They form colorless solutions with aqueous alkalies, inwhich the leuco indophenol is easilyroxidized even in contactwith atmospheric oxygen to the correcolored indophenols. v

. The most probable formula" for these i leucoindophenols is the following:

These novel dihydroindole-indophenolic bodies produce in the polysulfide melt very valuable sulfur dyestuffs which are described and claimed in my co-pending application,-

Serial- No.-144,187 filed of even date, which has matured into Patent 1,725,046 dated Aug. 20, 1929.

Bath the lndophen'ols and their leuco do i rivatives produce "the same dyestuffs, the ing dophenol being probablypriniarily reduced in the polysulfide melt to the leuco compound;

Dueto this similar behavior-and the ease with which the indophenols andtheir leuco compounds are converted one into the other I wish it to be understood that the term indophenolic body is used herein as generic to both the indophenols and their leuco derivatives. V 1

Amongst the different processes described above which lead to my novel dihydroindole indophenols I might mention as particularly useful the jointoxidation of a dihydroindole compound with a p-amino-phenol in aqueous mlneral acid solution by means N cme formula in which R- stands for an alkyl or aryl radicle, produce with p-an'iino-phenols IIIdOphQHOlIC bodies found suited for the production of valuable dyestufi's.

The Q-aryL or 2-alkyldihydroindole-indophenolic bodies have in the form of their leuco compounds most probably the formula ona These leuco compounds crystallize from di luted sodium. chloride solutions in yellow needles. Their alkaline solutions are easily oxidized by atmospheric oxygen, forming intense red solutions of'the corresponding indophenols.

The following examples will further illustrate my invention, the. parts being by weight.

Example 1.-2O parts 2-1nonomethyl-dihydroindole are suspended in 600 parts water and dissolved by the additon of about 370 art-s 19 B. hydrochloric acid; a hydrocii phenol and then about 34 parts B. sulfuric acid added.- This solution is then quickl run into an ice cold aqueous solutlon o 29 parts sodium bichromate and about parts 30% caustic soda solution added. A dark red solution of the indophenol is obtained; this reduced to the leuco compound by the addition of sodium sulfhydrate, whereby the dark red color of the solution turns to a light yellow. This solution is then acidified with mineral acid to distinct Congo acid reaction, heated to 60 C., plenty of salt added and allowed to cool. The light yellow colored 2 monomethyl-dihydroindole-leucoindophenol separates, is

filtered of and washed with a sodium chlo ride solution.

soluble in water, alcohol and It is easily and crystallizes from a dilute sulfuric ac'i pa rticul arlyloric acid solution of 16 parts p-amino- A is filtered of! indophenol has most probably the formula:

CH.CHI

Ewample 2.l7 parts dihydroindole are suspended in 600 parts water and dissolved by the addition of about 370 parts 19 B6.

hydrochloric acid; a hydrochloric acid solution of 16 parts p-amino-phenol and then 34 parts 60 Be. sulfuric acid are added. The solution is now quickly run into an ice cold aqueous solution of 29 parts sodium bichromateand about 120 arts 30% caustic soda solution added. A ark red solution of the indophenol is obtained, this is reduced to the leuco compound by the addition of sodium sulfhydrate, whereby the dark red colorot the solution turns to a light yellow. This solution is then acidified with mineral acid to distinct Congoacid reaction, heated to about 60 C., plenty of ice added and allowed to cool. The yellow colored dihydro indole-leuco-indophenol separates and is filtered oil and washed with a sodium chloride solution.

The so obtained leucoindophenol is a yellow powder, which by crystallization from a dilute sodium chloride solution is obtained as beautiful needles. It is easily soluble in water, alcohol and sulfuric acid. It forms With a ueous caustic soda a colorless solution, which y standing in the air soon turns intense redwith formation of the indophenol.

The dihydroindole-leucoindophenol has most probably the formula N H cre PIC-GILT Example 3.20 parts 2-monophenyl-dihydroindole are suspended in 600 parts water and dissolved by thenddition of about 370 parts 19 B. hydrochloric acid; a hydrochloric acid solution of 16 parts p-amino-phenol and about 34 parts 60 B. sulfuric acid are now added. This solution is then quickly run into an ice cold aqueous solution of 29 parts sodium bichromate and about 120 parts 30% caustic soda added. A dark red solution of the indophenol is obtained; this is reduced to the leuco compound by the addition of sodium sulfhydrate, whereby the dark red color r of the solution turns to a light yellow. The solution is then acidified with mineral acid to distinct Congo acid reaction, heated to about 60 C., plenty of salt added and allowed to cool. The yellow colored 2-monophenyldihydroindolesleucoindophenol separates, it and preferably washed with a sodium chloride solution. The so obtained 2-monophenyl-dihydroindole leucoindo henol is a yellow powder, which by crystal intion from diluted sodium chloride solution is obtained as beautiful, needles. it is easily solublein water, alcohol and sulfuric acid.-

sodium bichromate'and about 120 parts 80% A blue solution of the causticsoda added. indophenol is obtained; this is reduced to'the leuco compoun'd'by the. addition of sodium sulfhydrate, whereby the blue color of the solution turns to a light yellow. This -solu-- tion is then acidified with mineral acid to distinct Congo acid reaction, heated to 60 0.,

plenty of salt added and allowed to cool. The yellow colored L2-dimethyl-dihydroindoleleucoindophenol separates, is filtered ed and preferably washed with a sodium chloride 7 solution.

The so obtained leucoindophenol is yellowish powdeiy which by crystallization from dilute sodium chloride solution is obtained as beautiful needles. It is easily soluble in water, alcohol and sulfuric acid. It forms with aqueous caustic soda a colorless solution,

which by standing in the air soon becomes in tense blue with formation of the indophenol.

The 1-2-diniethyl dihydroindole leucoinidophenol has most probably the formula Example 5.2O parts 2-monomethyl-dihydroiiidole are suspended in=600 parts water and dissolved by the addition of'about 370 parts of 19 Be. hydrochloric acid, a solution of 37 parts 2-6-dichlorop-aminophenol sulfate and about 34 parts 60 Be. sulfuric acid are now added. This solution is now quickly run into an ice cold aqueous solution of 2-9 parts bichromate andabout 120 parts 30% caustic soda added. A dark red solution of the indophenol'is obtained, this is reduced to the leuco compound by the addition of sodium sulfhydrate, whereby the dark red color of the solution turns to a light yellow. This solution is then acidified with mineral acid to This solution is now quickly run distinct Congo acid reaction, heated to 60 6.,

plenty of salt added and allowed to cool. The

yellow I colored 2+mono-methyl-dihydroindole-leuco-dichloro-indophenol separates. It

is filtered off and preferably washed with a.

sodiumchloride solution. I

The so obtained leuco indophenol is a yellowish powder, which by crystallization from dilute sodium chloride solution is obtained as beautiful needles.- It is easily soluble in water, alcohol and sulfuric acid. It forms The Q-methyl-dihydroindoledeuco-dichloro-indophenol has-most'iprobably the forniu laz l I c 7 g H I III OCO HQHS H0 9 cm mample 6.550 parts 66 Be. sulfuric acid are cooled to about C. and parts2- inonoinethyl-dihydroindole added followed by a gradual addition er 20 parts quinone chlor-imid. The reaction mass issti-rred for with aqueous caustic soda a colorless solution, 7 which by standing in the air turns intense red with formation of the indophen'ol.

a short while, thenpoured into caustic soda and reduced with sodium still-hydrateuntil the deep red solution of theindophenolhas been transformed into the light yellow solution of the lGLLCOlIlClOPlZlQIlOl. It isthen acic i-- fied with mineral acid to distinct Congo acid reaction, plenty of salt added and allowed to cool. The yellow coloredQ-monomethyldihydroiiidole-leucoindophenol separates, it

is filtered off and preferablywashedwith a sodium chloride solutioin It is identical with the leucoindoplienol obtained in Example 1.

I claim: 1. The process of producing a dihydro-indole indophenolic body which comprises sub- Jecting a dihydro-indole of theformula R1 OER oR.

wherein R stands for hydrogen, an alkyl, aryl or an aralkyl group and R lstands for a henzene nucleus which may be substituted by alkyl,aryl, aralkyl, halogen or other monoralent group, and an aromatic para-ainino-hydroxy compound to a reaction leading to the formation of an indophenol.

2. The process of producing a dihydro-indole-indophenolic body which comprises subjecting a dihydroindole of the formula:

wherein stands for hydrogen, an alkyl,

i an

aryl, or an aralkyl group and an aromatic para-aniino-hydroxy-compound to a reaction leading to the formation of an indophenol.

3. As new products dihydroindole leucoindophenole having most probably the for- 1nula:

wherein R stands for an alkyl, aralkyl or aryl group which crystallize from dilute sodium chloride solutions in yellow needles, are easily soluble in water, alcohol and sulfuric acid and form with aqueous caustic soda colorless solutions which by standing in the air change to darkv red solutions containing the corresponding indophenols.

5. As a new product the 2-monophenyl-dihydroindole-leuco-indophenol having most probably the formula which crystallizes from dilute sodium chloride solution in yellow needles, is easily soluble in water, alcohol and sulfuric acid and forms with aqueous caustic soda colorless solutions which by standing in the air change to dark red solutions containing the 2nionophenyl-dihydroindole-indophenol.

(1'. As new products, dihydroindole-indophenolic bodies, which in form of their leuco derivatives have most probably the formula:

wherein R stands for hydrogen, an alkyl, aryl, or an aralkyl group, and R stands for a benzene nucleus to which NH and NR are in para-position and which may be substituted by alkyl, aryl, aralkyl, halogen or other monovalent group and which can be obtained by the process of claim 1.

In testimony whereof, I aflix my signature.

FRITZ BALLAUF. 

